1. Technical Field
The present disclosure relates to an apparatus for performing an electrosurgical procedure. More particularly, the present disclosure relates to an electrosurgical apparatus including an end effector assembly having a pair of jaw members that provide a mechanical advantage at the end effector.
2. Description of Related Art
Electrosurgical instruments, e.g., electrosurgical forceps (open or closed type), are well known in the medical arts and typically include a housing, a handle assembly, a shaft and an end effector assembly attached to a distal end of the shaft. The end effector includes jaw members configured to manipulate tissue (e.g., grasp and seal tissue). Typically, the electrosurgical forceps utilizes both mechanical clamping action and electrical energy to effect hemostasis by heating the tissue and blood vessels to coagulate, cauterize, seal, cut, desiccate, and/or fulgurate tissue. Typically, one or more driving mechanisms, e.g., a drive assembly including a drive element, is utilized to cooperate with one or more components operatively associated with the end effector to impart movement to one or both of the jaw members.
To facilitate moving the jaw members from an open position for grasping tissue to a closed position for clamping tissue (or vice versa) such that a consistent, uniform tissue effect (e.g., tissue seal) is achieved, one or more types of suitable devices may be operably associated with the electrosurgical forceps. For example, in some instances, one or more cam members, e.g., a cam pin, may operably couple to the drive element, e.g., a drive rod, wire, cable, etc., and operably couple to a cam slot that is operably associated with one or both of the jaw members. Typically, the cam slots are operably disposed on proximal end of the jaw members. In certain instances, to facilitate movement of the jaw members, the proximal ends of the jaw members are configured to extend outside of the shaft profile. In this extended position, the proximal ends of the jaw members are commonly referred to as “flags.”
In certain instances, the shaft may bend or deform during the course of an electrosurgical procedure. For example, under certain circumstances, a clinician may intentionally bend or articulate the shaft to gain a desired mechanical advantage at the surgical site. Or, under certain circumstances, the surgical environment may cause unintentional or unwanted bending or flexing of the shaft, such as, for example, in the instance where the shaft is a component of a catheter-based electrosurgical forceps. More particularly, shafts associated with catheter-based electrosurgical forceps are typically designed to function with relatively small jaw members, e.g., jaw members that are configured to pass through openings that are 3 mm or less in diameter. Accordingly, the shaft and operative components associated therewith, e.g., a drive rod, are proportioned appropriately. That is, the shaft and drive rod are relatively small.
As can be appreciated, when the shaft is bent or deformed (either intentionally or unintentionally) the frictional losses associated with “flags” extending through the shaft profile may be transferred to one of the drive rod, drive element, and/or a spring operably associated with the drive assembly, which, in turn, may diminish, impede and/or prevent effective transfer of the desired closure force that is needed at the jaw members. Moreover, the frictional losses may also lessen the operative life of the spring, which, in turn, ultimately lessens the operative life of the electrosurgical instrument.